1. Field of the Invention
The present invention relates to an ink sheet for heat-sensitive transfer recording material containing a specific azo dye, a heat-sensitive transfer recording method, an ink cartridge and a novel azo dye.
2. Description of the Related Art
In recent years, as image recording materials there have been mainly used materials for forming a color image in particular. In some detail, ink jet process recording materials, heat-sensitive transfer type image recording materials, recording materials using electrophotographic process, transfer type silver halide photographic materials, printing inks, recording pens, etc. have been widely used.
In these color image recording materials, colorants (dye or pigment) of additive or subtractive primaries are used to reproduce or record a full-color image. However, it is the status of quo that there are no colorants which have absorption characteristics allowing the realization of desirable color reproduction range and can withstand various working conditions. It has thus been keenly desired to have improvements in this respect.
Heat-sensitive transfer recording processes include a process which comprises heating a heat-sensitive transfer material comprising a heat-fusible ink layer formed on a base film (support) using a thermal head to melt the ink so that it is recorded on the image-receiving material and a process which comprises heating a heat-transfer material comprising a dye-providing layer containing a heat-movable dye formed on a base film to cause the dye to be heat-diffused and transferred on the image-receiving material. The latter heat-sensitive transfer recording process involves the change of the energy applied to the thermal head, making it possible to change the transferred amount of the dye. Thus, tone recording can be easily effected. This heat-sensitive transfer recording process is favorable particularly for full-color recording of high quality images. However, the heat-movable dyes to be used in this heat-sensitive transfer recording process have various limitations. There are extremely few heat-movable dyes which satisfy all the requirements.
These heat-movable dyes are required to have spectral characteristics desirable for color reproduction, be easily transferred, be fast to light, heat and various chemicals, be easily synthesized and easily form a heat-sensitive transfer recording material. It has thus been desired to develop a dye having excellent spectral characteristics and a high lightfastness.
On the other hand, azo dyes having an azo bond in the 4-position of pyrazole are disclosed in JP-A-2005-162812, JP-A-2003-41160, JP-A-2003-41161, JP-A-2003-41162, JP-A-2003-41163, JP-A-2003-128953, JP-A-2002-194258 and JP-A-8-231867. Azo dyes having 5-aminopyrazole as a coupling component are disclosed in JP-A-2005-226022, JP-A-2003-221535, JP-A-2003-128953, JP-A-8-90939, JP-A-6-106862, JP-A-2-24191 and JP-A-1-225592. However, none of these patent references refer to the fact that the azo dye of the following formula (1) can be effectively used in heat-sensitive transfer recording process.